Taxonomy & naming
Betta anabatoides was described by the Dutch colonial physician and prolific ichthyologist Pieter Bleeker in 1851, in the Natuurkundig Tijdschrift voor Nederlandsch Indië (volume 1: 259–275), based on material from Borneo. The specific epithet anabatoides means 'resembling Anabas' — a reference to the climbing perches, which the stout, high-backed body of this species recalls. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) records Betta anabatoides Bleeker, 1851 as the valid name; the authority is unparenthesised because the species was described in Betta, the genus in which it remains.
The species gives its name to the anabatoides species group, a clade within Betta characterised by a relatively short, deep body (body depth exceeding 31% of standard length), the absence of a chin bar, an unpatterned throat, iridescent gold opercular scales in life, caudal-fin rays that project beyond the fin margin, and a dorsally convex head profile. The group was defined and its members reviewed by Tan & Ng (2005) in the Raffles Bulletin of Zoology, the landmark monograph on the fighting fishes of Singapore, Malaysia, and Brunei. B. anabatoides is distinguished within the group by its particularly thick-set proportions (body depth 30.5–33.7% SL), a head pattern featuring a dark preorbital stripe that runs continuously from the black lower lip, through the eye, and onto the opercle, and faint gold iridescent scaling on the gill cover visible in living individuals. A minority of caudal-fin rays extend beyond the posterior fin margin as short filamentous projections. The species is a member of the family Osphronemidae and, like all bettas, is a labyrinth fish — it possesses a suprabranchial labyrinth organ that allows direct aerial respiration.
Morphology
Betta anabatoides is a robustly built fish, notably more stocky than the elongate body plan typical of many wild betta species. FishBase records a maximum size of 3 in standard length, making it one of the largest representatives of its family outside the fighter betta complex, and consistent with its common name 'giant betta' in some hobby circles. The body depth is proportionally high — exceeding 31% of SL by definition of the group — giving the fish an almost perch-like silhouette, which is precisely what Bleeker's epithet commemorates.
The head is broad and dorsally convex, with a wide gape suited to taking sizeable prey. The diagnostic head pattern includes a distinct dark preorbital stripe running from the black lower lip, through or below the eye, and continuing onto the opercle as a continuous lateral facial stripe; this distinguishes B. anabatoides from related group members such as B. midas. In living individuals the opercle carries faint but visible gold iridescent scales. The caudal fin is rounded, with some median rays extending as short projections beyond the fin margin — a group character. Finnage is otherwise unremarkable: broad pectoral fins, a relatively short dorsal, and an anal fin that extends well along the ventral midline. Ground colour and precise colour pattern in wild fish are difficult to characterise comprehensively because authentic specimens are genuinely scarce in aquaria and photographic records, and the species is frequently misidentified.
Habitat
Betta anabatoides is known from the lower Barito River basin in South Kalimantan and from the Kotawaringin, Katingan, Sampit, Mentaya, and Kahayan river basins in Central Kalimantan — all in the Indonesian portion of Borneo. These are lowland blackwater systems, characterised by slow or nearly stagnant water heavily stained with humic and fulvic acids leached from decomposing peat and leaf litter. The water is typically very soft, highly acidic, warm, and low in dissolved oxygen — conditions produced by the surrounding peat-swamp forests that drain into these rivers.
FishBase records the depth range as approximately 3 ft, confirming a shallow, near-surface existence consistent with the labyrinth organ's role in supplementing gill respiration with air breathed at the surface. Temperature is reported in the range of 81–86 °F, and pH in the range of 4.5–7.5, though the lower end of that pH range — acid blackwater conditions — is most representative of the undisturbed peat-swamp habitat. The habitat of related anabatoides-group species (notably B. midas, studied in the field by Seriously Fish authors) confirms the general picture: shallow blackwater rivers flowing through intact peat-swamp forest, with pH as low as 4.1, depth from 8 in to 7 ft, dim light beneath a closed forest canopy, and substrates of leaf litter and root tangles. B. anabatoides likely selects similar microhabitats — sheltered, vegetated, and structurally complex margins rather than open midchannel.
As a labyrinth fish, B. anabatoides is well adapted to the oxygen-poor conditions of stagnant swamp water. The suprabranchial organ allows it to breathe atmospheric air directly, reducing its dependence on dissolved oxygen and enabling survival in waters that would suffocate most gill-only fishes. Access to the water surface is therefore an ecological necessity.
Feeding
In nature, Betta anabatoides is a carnivore, feeding on insects and small invertebrates — aquatic insect larvae, surface insects, small crustaceans, and other invertebrates encountered in the leaf litter and root-tangle microhabitats it inhabits. The wide gape of the species relative to most small labyrinth fishes allows it to take proportionally larger prey items.
In the aquarium, the species — like related blackwater bettas — strongly prefers live and frozen foods and can be reluctant to accept dry foods without conditioning. Suitable prey items include Daphnia, Artemia nauplii, bloodworm (chironomid larvae), Grindal worm, and small earthworms. A diet centred on high-protein live and frozen foods is the most reliable approach for maintaining condition and encouraging reproductive behaviour. Prepared foods may be accepted by established fish but should not be relied upon as the sole diet for this species.
Mating
Betta anabatoides is a paternal mouthbrooder — the defining reproductive character of the anabatoides species group. Courtship in mouthbrooding bettas differs substantially from the bubble-nest complex of the splendens group. The male does not construct a surface nest; instead, the pair engages in the typical anabantoid embrace, in which the male wraps his body around the female to fertilise the eggs as they are released. The fertilised eggs are then collected into the male's mouth.
Male displays during courtship are less exuberant than in many bubble-nesting species; there is no nest to defend and no site-based rivalry of the same kind. Females should be well conditioned on live foods before pairing, as a female in poor condition may fail to spawn or produce an undersized clutch. Once spawning and collection are complete, the female's role in reproduction is finished; she may be removed or the pair separated to avoid stress on the brooding male.
Breeding
After the embrace and egg collection, the male holds the fertilised eggs in his buccal cavity and broods them through hatching and the early free-swimming stage — a period of approximately one to two and a half weeks depending on temperature. During this time the male eats nothing, relying on metabolic reserves to sustain himself while the eggs develop in his mouth. Disruption to the male during brooding (netting, aggressive tankmates, sudden parameter changes) risks causing him to spit and abandon the clutch or swallow it prematurely.
Breeding is most reliably achieved in a dedicated species or pair tank with very soft, acidic water replicating the blackwater conditions of the home habitat: pH in the range of 4.5–6.0, minimal hardness, and temperature in the upper 20s Celsius. Gentle, low-flow filtration (a sponge filter) and heavy use of Indian almond leaves or peat to acidify and stain the water are standard practice. A heavily planted or structured tank with areas of refuge for both fish reduces stress during courtship. When the male releases free-swimming fry after the brood period, the young are relatively large compared with bubble-nesting betta fry and can often take Artemia nauplii as a first food, simplifying rearing compared with species whose fry require infusoria.
In the aquarium
Betta anabatoides is an infrequently encountered species in the hobby, partly because genuine specimens are scarce and partly because the trade supply is complicated by persistent misidentification — fish labelled B. anabatoides have often proved to be B. midas or other related taxa. Acquiring confirmed specimens from specialist breeders is therefore important both for keeping the correct fish and for supporting accurate husbandry records.
Once correctly identified, the species requires the same conditions as other blackwater bettas from Borneo: very soft, acidic water (pH 4.5–6.5), warm temperatures (79–86 °F), dim lighting, a tight-fitting lid (labyrinth fish jump readily), surface access at all times, and minimal water movement. Indian almond (Terminalia catappa) leaves, peat filtration, or blackwater extract can maintain the appropriate chemistry and provide tannins that appear to support immune health and reduce stress in these fish. The tank should be structured with dense planting or leaf litter and refugia so that both sexes have retreat options. Because B. anabatoides is larger than most wild bettas — up to 3 in — it requires a proportionally larger tank than the common advice for small wild Betta species; a dedicated tank of 23.5 in or more in length is appropriate for a pair.
Tankmate selection demands care. The species is best kept as a pair or in a species tank; conspecific males may fight, and mixing with small, fast, or nippy fish risks either predation of small tankmates or stress to the betta itself. The paternal brooding behaviour means that any tank disturbance — including aggressive or boisterous tankmates — during the brood period can result in clutch loss.
Conservation
Betta anabatoides is assessed as Least Concern (LC) on the IUCN Red List, assessed 5 December 2018. The assessment reflects a distribution across multiple river basins in Kalimantan and a presumed population size large enough that it does not currently meet thresholds for a threatened category. FishBase confirms the LC assessment, citing version 2025-2 of the IUCN Red List.
Nonetheless, the broader habitat context gives reason for watchfulness. The peat-swamp forests of Kalimantan are among the most rapidly degraded ecosystems in Southeast Asia, lost to logging, palm-oil agriculture, drainage, and fire. The blackwater rivers and peat swamps that B. anabatoides depends upon are shrinking throughout the island. Alongside habitat loss, collection for the ornamental-fish trade has historically removed individuals from multiple basins. While the current LC status suggests the species is not facing imminent collapse, habitat loss across Borneo is rapid, and peat-swamp specialists with limited habitat plasticity are at elevated risk if forest cover continues to decline. Supporting captive populations through responsible breeding, and sourcing fish from confirmed captive lineages rather than wild-caught specimens, are straightforward contributions aquarists can make to reducing wild collection pressure.